Problem: $ { {-2} \times \left[\begin{array}{rr}{-1} & {0} \\ {1} & {1}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-2}\times{-1} & {-2}\times{0} \\ {-2}\times{1} & {-2}\times{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{2} & {0} \\ {-2} & {-2}\end{array}\right]}$